This invention relates in general to a solid state fast frame recorder which records an event at a fast frame rate and plays back the event at a slower frame rate so that the event may be analyzed. More particularly, this invention relates to a solid state fast frame recorder having a solid state imager and a solid state memory for recording temporally nonconsecutive image frames from the imager according to a preselected program.
Fast frame recorders are useful for motion analysis of an event. A fast frame recorder records a great number of images during an event at a high or fast image frame rate and reproduces the image frames more slowly at a lower frame rate. Thus, any movement occurring during the event may be analyzed in a step-by-step progression. Applications for a fast frame recorder include, malfunctions in high speed machinery, movements of an athlete, testing of safety equipment, shattering an object, etc. One type of fast frame recorder is disclosed in commonly assigned U.S. Pat. No. 4,496,995, issued Jan. 29, 1985. As disclosed in the latter patent, the fast frame recorder-motion analyzer includes a video camera, a variable speed magnetic tape processor and a video display monitor. The camera is read out in block format so that a plurality of lines of video information that correspond to rows of photosites in the camera solid state imager are simultaneously recorded on magnetic tape in parallel longitudinal tracks. During play back, the magnetic tape is played back at a reduced tape speed. A plurality of parallel video signals reproduced from a plurality of parallel tracks on the tape, are processed into a serial video signal which may be used with standard video monitors. Although a magnetic tape, fast frame recorder is advantageous because of its ability to record a large number of image frames and because of the non-volatility of the image storage, there are limitations to magnetic tape recording. Such a fast frame recorder tends to be costly since, in recording and reproducing a plurality of parallel video signals, separate record and reproduce signal processing circuitry must be provided for each video signal channel. Since the video signals are recorded directly on magnetic tape in an analog format, picture quality is degraded significantly due to induced flutter and other noise, due to reduced bandwidth and increased phase distortion and due to imprecisely recorded pixel signal values.
In many applications where the use of a fast frame recorder is appropriate, the event to be recorded is random in nature and may occur at random moments during an extended period of time. Due to the inherent recording length constraints of a magnetic tape fast frame recorder, its ability to capture randomly occurring events may require the recording of a large number of image frames which are unnecessary for the analysis of the event. During playback, the unwanted images must be scanned before images relating to the event can be analyzed, resulting in a waste of time, money and recording tape. Moreover, certain events may be incapable of being recorded due to the length of elapsed time between recordable events.